Sharpening attachment for a cloth cutting machine



Jan. 17, 1956 RQCKWQQD r 2,730,850

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE 6 Sheets-Sheet 1 FiledDec. 17 1949 INVENTORS Albert M. Rockwood Robert M. Conklin Mm, $1M 8.14

AGENTS.

17, 1956 v K A. M. ROCKWOOD ETAL 2,730,850

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 6Sheets-$heet 2 FIGURE 2 INVEN T ORB Albert M. Rockwood BY Robert M.Conklin M, M ,5 A,

AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 n6 Sheets-Sheet 5 IN VEN TORS Albert M. Rockwood F/GURE 4 BY Robert M.Conklirn m, 9M 3 A AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL SHARPENING ATTACHMENT FOR A CLOTHCUTTING MACHINE Filed Dec. 17, 1949 6 Sheets-Sheet 4 INVENTORS Albert M.Rockwood BY Roben M. Conklln F/GURE 6 FIGURE 5 Hllllll AGENTS.

J 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE 6 Sheets-Sheet 5 FiledDec. 17, 1949 F/GURE 7' FIGURE 8 INVENTORS Albert M. Rockwood Robert M.Conklin m w 15 in AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 6Sheets-Sheet 6 FIGURE 9 F/GURE /0 Albert M. Rockwood BY Robert M.Conklin won, ykum a...

AGENTS.

United States Patent t SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINEAlbert M. Rockwood and Robert M. Conklin, Columbus, Ohio, assignor, bymesne assignments, to The Wolf Mfirlchine Company, Cincinnati, Ohio, acorporation of O '0 Application December 17, 1949, Serial No. 133,606

3 Claims. (Cl. 51-249) This invention relates to a cloth-cutting machinehaving a reciprocating knife blade, and more particularly to anautomatic sharpening device for grinding the knife blade.

Many attempts have been made to replace the customary method ofsharpening the knife by drawing an emery stick downward along the blade.However, the various sharpening mechanisms have had the disadvantages ofobscuring the view of the operator when operating the cutting machine orbeing required to be detached from the machine when not in use. Otherdevices of the prior art have been manually operated, with theconcurrent danger of injury to the operator by accidental contact withthe knife blade.

Another problem which has not been satisfactorily met is the effect ofthe wearing away of the grinding means and the knife edge after a periodof use. For the best cutting eifect the included angle of the bevel onthe knife edge should be not less than 10 nor more than 25. In priordevices the gradual wearing away of the grinding means and knife edgehas resulted in a change in the bevel of the knife edge and a resultinginferior cutting action. Also, since the toe of the knife blade operateson the cloth with a chopping effect, it is desirable to sharpen thebottom end of the knife blade, and until now no satisfactory method hasbeen found to utilize automatic knife sharpening means for this purpose.

One object of the present invention is to provide sharpening means,mounted on a cloth cutting machine, which move vertically along thelength of the knife blade as the grinding wheels revolve, and during thesame operation grind the toe of the knife blade.

Another object is to provide a reciprocating mechanism for thesharpening means whereby the driving torque is automaticallydisconnected and the sharpening mechanism braked, after the sharpeningcycle is completed.

A further object is to provide a means for operating the sharpeningmechanism in which all gears are shielded from any abrasive dust.

Yet another object is to provide a novel support for the grinding meanswhich automatically compensates for Wear of the grinding means so thatthe knife blade is always ground at the optimum angle for best resultsin cutting cloth.

Other objects and advantageous features will be apparent from thefollowing detailed description and the accompanying drawings whereinsimilar characters of reference designate corresponding parts, andwherein:

Figure 1 shows a side elevation of the machine with the presser footlowered to the position where it is resting on the base.

Figure 2 is a vertical sectional view of the machine, showing thepresser foot in the raised position.

Figure 3 is a view of the machine taken along the line 33 of Figure 2.

Figure 4 is a sectional view taken along the line 4-4 of Figure 3.

Figure 5 is a sectional view taken along the line 5--5 of Figure 1.

2,730,850 Patented Jan. 17, 1956 Figure 6 is a sectional view takenalong the line 6-6 of Figure 2.

Figure 7 is a sectional view taken along the line 77 of Figure 6.

Figure 8 is a sectional view taken along the line 8-8 of Figure 2.

Figure 9 is a view of the grinding wheels, showing them in operatingposition to contact the knife blade.

Figure 10 is a view similar to Figure 9, showing the grinding wheels inthe inoperative position out of contact with the knife blade.

Figure 11 is a front elevational view of the larger of the two grindingwheels used in this invention;

Figure 12 is a side elevational view of the larger of the two grindingwheels used in this invention.

Figure 13 is a front elevational view of the smaller of the two grindingwheels used in this invention; and

Figure 14 is a side elevational view of the smaller of the two grindingwheels used in this invention.

The improved cloth-cutting machine of this invention as shown in Figure1 comprises a base 15, a vertical standard 16 mounted thereon, a housing17 for the motor and knife reciprocating mechanism, and a removable unit19 containing the sharpening mechanism. The removable unit 19 is securedto housing 17 by means of screws 200 passing through flanges 2431extending outwardly from the sides of removable unit 19.

The base consists of a pivoting front toe plate 20, a base plate 18, andspring-mounted rollers 22 which are mounted in the base plate to providefor easy movement of the machine during the cloth-cutting operations.

The standard 16 is provided with a vertical slot lined with a wear strip21 which guides the reciprocating knife blade 24 during its movement.

A housing 17, made in three parts, is attached to the upper part of thestandard 16 and encloses an electrical motor, a fan, and a centrifugalswitch. Mounted at the bottom of the housing is a toggle switch 202 tocontrol the motor, and a handle 18 for guiding the machine during thecloth-cutting operation. On top of the housing are a carrying handle 28and a suitable terminal block 29 to supply electric power to the motor.

Knife reciprocating mechanism As illustrated by Figures 2 and 3, theelectric motor drives a shaft 30 on which is mounted a fiy-wheel andcrank assembly 32. The fly-wheel and crank assembly comprises acounterweight 33 to which a drive rim 34 is connected by suitablefastenings. A crank pin 35 is connected to the fly-wheel and crankassembly 32, and supports the connecting rod bearing 37 and retainingscrew 38. This bearing 37 supports connecting rod 39 which is held inplace by lock nut 41.

The connecting rod supports between its arms the crosshead 43, and itsliner 45, by means of a bushing 42 and a through bolt 46. A splitconnecting rod is used to reduce wear on the bushing. The through bolt46 is held in position by anchor nut 47 which, in turn, is secured tothe connecting rod by screws 49. The crosshead 43 and liner 45 areseparated from the connecting-rod arms by wipers 50. Projecting from thelower end of the crosshead 43 is a lug 51 to which the knife blade issecured by suitable fastening means, such as a bolt and nut 52.

In its vertical movement the crosshead 43 is guided by gibs 54 which arefastened to the front shell casting 55. The alignment of the crossheadrequires a delicate adjustment of the gibs so that the knife blade willbe properly positioned relative to the standard or satisfactory cuttingof the cloth and will not bind on the wear strips in the standard. Inthe novel device of-the present 'of sharpener housing 66.

invention this adjustment may be accomplished quickly and easily in thefollowing manner as shown in detail in Figure 4:

Gib. springs 56 are fitted around the adjusting pins 57 and are held incontact with the gibs by spring retainers 59 which are screwed into thefront shell casting 55. The pins 57 are located in line with the gibhold-down screws 60 so that the locking action of these screws, whenapplied, will not exert a torque on the gibs which would move them outof alignment. Nuts 61 are fitted onto the ends of the adjusting pins 57which project through the spring retainers 59. To adjust the gibs 54,the holding screws 60 are loosened and the gibs positioned by means ofthe nuts 61 on the ends of the adjusting pins 57. The gibs are thanlocked in position by tightening the holding screws 60.

The crosshead 43 is lubricated by means of elbow cups 62 mounted on thefront shell casting 55. The oil is conveyed by copper tubes to therecesses 64 in gibs 54 and through holes to the sliding surface of thegibs. Holes in the side of the c'rosshead allow the oil to pass throughthe liner 45 and lubricate the bearing surface, which is the bushing 42.Any abrasive particles present will wear this steel bushing rather thanthe bronze liner, and for this reason, it is so constructed as to bereadily replaceable.

Presser foot shaft Positioned in front of the knife blade 24 andstandard 16 is the presser foot shaft 65, slidably mounted in a bearingwithin the lug 72 which projects from the front This is shown inv Figure5. At the bottom of the shaft 65 is mounted a presser foot 67, in such amanner that the foot will contact cloth to be out only in the vicinityof the knife blade. The rear portion of the presser foot is divided inorder that the foot may clear the knife blade. The shaft 65 also servesas a safety guard when lowered to the position in which the presser footcontacts the cloth, as in this position the opertaor is protected fromaccidental contact with the knife blade. At the upper end of the shaft65 a handle 68 is mounted for convenience in raising and lowering thepresserfoot. The shaft 65, together with the attached presser foot 67,is held in any desired position by means of lock pin 70, which is forcedagainst the shaft 65 by the action of spring 71. Spring 71 and lock pin70 are held in position in the sharpener housing casting 66 by nut 73'threaded to fit the casting. Yoke 74 fits into the threaded center holeof lock pin 70. Handle 76 is mounted between the arms of the yoke 74 bya stud and-nut 77 and pivots by means of pivot stud 78 which holds it toa lug projecting from sharpener housing casting 66. Thus movement of thehandle 76 toward the machine will force the yoke 74 and connected lockpin 70 out of contact with the presser foot shaft 65, permittingvertical movement of the shaft. As the handle 76 is released, the actionof spring 71 against the lock pin 70 holds shaft 65 in any desiredposition.

When the foot shaft is lowered to the position where the presser foot 67is resting on the base 15, the groove "75 near the upper end of theshaft 65 is moved into a position whereby it may be engaged by the lockpin 70. As the lock pin 70 moves into this groove the resulting pivotaction permits the release handle '76 to move a greater distance fromthe machine to a position where itno longer blocks an interlock controlrod 79. When the presser foot is in raised position release handle 76 isimmediately under interlock control rod 79 and prevents it from movingdownwardly to actuate the sharpener mechanism. When the interlockcontrol rod 79 is free to move downward, the sharpener mechanism may beoperatcd. It can thus be seen that the sharpener mechanism can beoperated only when the presser foot is in its lowest position, and thereis no possibility of injury to the presscr foot or the grinding wheelsby accidental contact of these parts during the grinding operation. Suchan interlock Sharpener mechanism As shown in Figures 6 and 8, thesharpener mechanism is actuated by the starting lever 80, which ispivotally connected to the upper end of the interlock control rod 79.The opposite end of the starting lever 80 is rotatably fastened by meansof stud 81 to a collar welded to support plate 83.

Spring loading pin 84, which is an integral part of the starting lever80, extends over the actuating pin 85. As the starting lever 30 isdepressed, pin 84 bears on the actuating pin 85 which slides downward inbushing 86 mounted in support plate 83, thereby compressing fric tionwheel spring 87 into sliding block 88 and forcing the block assemblydownward along guide pins 90 and 91 until the rubber tire on frictionwheel 92 contacts the fly wheel rim 34 which supplies driving torque tothe sharpening mechanism. Spring 87, which is retained in the slidingblock 88 by spring-retainer plates, serves to compensate for wear of thefriction wheel 92. Drive pulley shaft 95 is supported in sliding block88 by means of a bearing 97. Mounted on the end of shaft 95 is thefriction wheel 92. Sliding block 88 is held in place by snap rings onthe guidepins 90 and 91. Circular motion is transferred from fly wheelrim 34 to friction wheel 92, and by means of shaft 95 to the drivepulley 98. An O-ring belt 99 passing around pulley 98 drives pulley 100.

Bearing housing 101 supports stub shaft 102 on which are mounted pulleyand gear 104, shown in greater detail in Figures 6 and 7. The gear andpulley are pinned by pins 105, so that they rotate together. In meshwith gear 104 is gear 106 which is keyed to worm shaft 107 and held inplace by a stop nut. Worm shaft 107' is supported by two bearings 108and 109 located in bearing housing 101. A standard worm 111 is mountedon worm shaft 107, and is pinned to the shaft. The worm drives wormwheel 112 which is keyed to worm wheel shaft 113 and held in place by anelastic stop nut 114. Worm wheel shaft 113 revolves in a bearing 115mounted in bearing housing 101 and extends into the reversing driveshaft 116.

On the outside of the reversing drive shaft 116 is cut an endlessperipheral square thread 117 so that there is a section'extendingdownwardly which connects with a section extending upwardly which inturn connects with the downwardly extending section. These grooves limitthe travel of the sharpening mechanism. The reversing shaft 116 ispinned to the lower end of worm wheel shaft 113 and is suspended fromit.

Sharpener tube 119, reversing drive shaft 116, and a square grindingwheel drive shaft are arranged concentrically. Reversing shaft 116rotates freely inside of sharpener tube 119 which reciprocatesvertically. Grinding wheel drive shaft 120 is mounted in the sharpenertube 119 by means of the bearing 121 pressed in the end of the sharpenertube. Thus, drive shaft 120 moves vertically with sharpener tube 119 butmay also rotate with respect to it. The upper end of the drive shaft 120is.

guided by bearing 122, and as the shaft reciprocates it passes throughthe drive shaft guide 123 which is pressed into the end of reversingdrive shaft 116. Drive shaft guide 123 transmits rotary motion from thereversing drive shaft 116 to the grinding wheel drive shaft 120 by meansof the square hole therein contained through which square shaft 120passes. Sharpener tube 119 passes through end seal nut 124 which isscrewed into the bottom of sharpener housing 66. The threaded driveshaft 116, the gear mechanism, and the ball bushing 118 are shieldedfrom the abrasive effect of the grinding grit by the seal nut 124. Thelower end of sharpener tube 119 supports an adaptor plate 127 to whichthe grinding head is secured.

The reciprocating mechanism Vertical movement of the grinding mechanismis provided by means of a follower 128 which moves in the endlessperipheral groove 117 of the reversing drive shaft 116, as in Figure 8.The follower 128 is mounted in follower guide 129 and is forced incontact with the peripheral groove 117 by means of spring 130. Spring130 and follower 128 are held in place by retaining nut 131.

Follower guide 129 fits around sharpener tube 119 and is locked to thetube by stud 132 which passes through clamping flanges 134 and issecured by lock washer 135 and nut 136. A finger 137 on the followerguide 129 fits into the groove 138 in the support plate 83 so as toslide vertically but to prevent the guide 129 and sharpener tube 119from rotating. A flange 139 projecting outwardly from follower guide 129supports the adjustable pawl release screw 140, shown obscured by thepawl actuating pin 142 in Figure 8.

Automatic sharpening cycle mechanism The sharpening mechanism isautomatically disengaged from the fly wheel rim 34 after the completionof one vertical cycle of reciprocation in the following manner: A shaft141 is fitted through the support plate 83. Pa'wl actuating pin 142 isbrazed to the head of shaft 141. On the opposite end of shaft 141 aremounted pawl spacer 143, pawl actuating spring 144, and pawl 145 whichis secured to the shaft by key 146, the assembly being held in place bya snap ring 147. When the sharpener starting lever 80 is sufficientlydepressed, the spring loading pin 84 passes the notch in pawl 145 and isretained by it as the pawl actuating spring 144 forces the pawl intoposition.

Upon the completion of the sharpening cycle, as the follower guide 129moves upward, the adjustable pawl release screw 140 contacts the pawlactuating pin 142 forcing it upward, thereby rotating shaft 141 and pawl145 against the torque exerted by spring 144. This action releasesspring loading pin 84. Spring loading pin 84 and control lever 80 arethen forced upward by the friction wheel spring 87 and the tension ofO-ring belt .99 to their original position. Sliding block 88 in movingupward carries with it friction wheel 92 and removes it from contactwith fly wheel rim 34. As friction wheel 92 continues to move upward itcontacts the lug 149 aifixed to support plate 83 and is braked by it. Bymeans of this braking device, the sharpening mechanism is stopped at thehighest point of its travel, thereby insuring that the grindingmechanism will be out of the way of the operator when the machine isused for cloth cutting and that the grinding wheels are removed fromcontact with the knife blade, as will later be described.

This mechanism provides that if the machine should be stopped during itsgrinding cycle the sharpener starting lever could not be released untilthe grinding mechanism is returned to its highest position.

Grinding mechanism The grinding mechanism is enclosed within or attachedto grinding head housing 150. Thus its gears are protected from theabrasive effects of the dust resulting from: grinding. Rotating movementis furnished by driver gear 151, keyed to the bottom of grinding wheeldrive shaft 120. Gear 151 meshes with the gear 152 of grinder shaft 153.Grinder shaft 153 is supported within grinding head housing 150 by meansof a bearing 154 held in place by a snap ring 155. The top of grindershaft 153 fits snugly in adapter plate 127. Drive pulley 157 is threadedonto grinder shaft 153 and rigidly held in place by lock nut 158. Belowthis lock nut is mounted idler pulley 159, which is held in place by asnap ring.

The knife blade is ground by means of two abrasive 6 grinding wheels 160and 161, one of which is larger than the other. The grinding wheels areslidably mounted on shafts 162. The shafts are supported by bearings 164within the fixed bearing supports 165. Bearing supports 165 are securedby fastening means 166 to grinding head housing 150. The grinding wheels160 and 161 are positioned at an angle of about 10 degrees from thevertical and an angle of from 5 to 12 degrees from the plane of theknife blade 24. The arrangement of the grinding wheels 160 and 161 willgrind the blade 24 evenly at all points during the reciprocatingmovement and will also grind the toe of the knife blade. In priormachines the included angle of grind on the knife has varied with wear,but the positioning in the present machine will insure that as eitherthe grinding wheels or the knife blade wear, the angles at which thegrinding surfaces contact the knife blade will not change, but willremain constant and give optimum grinding results during a long periodof use. Shafts 162 also support pulleys 167, which are pinned to theshafts by taper pins. The grinding wheels are driven in oppositedirections by a single O-ring belt 168 which passes over drive pulley157, grinder shaft pulleys 167, and idler pulley 159.

Grinding wheels 160 and 161 are held in contact with the knife blade bymeans of a spring-loaded mechanism as in Figure 9. Bell cranks 169 aremounted on the grinding head housing 156 by pivot studs 170. Fingers 171are fastened to the bell cranks 169 by means of screws and pins. Slotsat the end of the fingers 1'71 fit around the ends of the grinding wheelshafts 162. Torsion springs 174 acting on the bell cranks 169 force thegrinding wheels 160 and 161 against the knife blade 24.

When the grinding mechanism is raised to its highest position, as inFigure 10, the position at which the mech anism is stopped by the brakeas described hereinbefore, the bell cranks 169 contact pins 175 whichare loaded by springs 176 and which are secured in place by snap rings.When the bell cranks 169 are forced into contact with the spring-loadedpins 175 the bell cranks are rotated in such a manner that the grindingwheels 16% and 161 are moved out of contact with the knife blade 24.However, when the grinding mechanism moves downward during the grindingcycle, the spring-loaded pins 175 move down until stopped by their snaprings, and as the bell cranks 169 move out of contact with thespringdoaded pins, the action of the torsion springs 174 forces the thegrinding wheels into contact with the knife blade. As the grindingwheels go below the upper limit of travel of 'the top of the blade, theyare forced in still further, thereby grinding the toe of the blade.

Operation 0 the sharpener When it is desired to sharpen the knife blade,the machine is removed from the cloth being cut. The presser footrelease handle 76 is moved toward the machine, allowing the presser footshaft 65 to move downward until the presser foot 67 rests on the baseplate 15. The presser foot handle 76 is released and moves outward fromthe machine until it clears the interlock control rod 79. The sharpenerstarting lever 36 can now be depressed until it locks through the actionof notched pawl 145 catching spring-loading pin 84. The interlockcontrol rod 79 now blocks the movement of handle 76 so that the presserfoot shaft 65 cannot be moved until the grinding cycle is completed. Inthis position friction wheel 92 contacts flywheel rim 34 and thegrinding mechanism is set in operation. As the sharpening mechanismbegins to descend, the rotating grinding wheels 160 and 161 contact theknife blade 24. When the mechanism is lowered a short distance beyondthe point where the grinding wheels begin to sharpen the toe of theknife blade, the mechanism begins to rise. As it reaches its upperposition the springloading pin 84 is released from notched pawl 145, and

the friction wheel 92 rises until it is braked. The foot shaft releasehandle 76 may now be moved toward the machine and the presser foot shaft65 raised. The machine is now ready for further cutting operations.

As can be seen by the foregoing description the improved machine of thisinvention 'is simple in construction, requires a minimum of maintenanceand any part may be conveniently and quickly replaced with no need fordelicate adjustment. It can be operated by a person without particularskill, with little danger of accidental injury from moving parts.

It will be understood that modifications may be made in the design andarrangement of the parts without departing from the scope of thisinvention, which is intended to be limited only as required by thefollowing claims.

What is claimed is:

1. In a cloth cutting machine having a reciprocating knife blade and amotor for moving said blade, a sharpening device comprising aperipherally threaded hollow shaft, a circular tube positioned coaxiallyoutside said threaded shaft, a follower secured to said tube andengaging the threads on said threaded shaft, a housing removablyattached to said machine and enclosing said tube, said housing and saidtube enclosing the peripheral surface of said threaded shaft, means forrotatably supporting said threaded shaft in said housing, powertransmission means between said motor and said shaft, a noncirculardrive shaft inside said threaded shaft, a guide member fixed to saidthreaded shaft having an opening complementary to said drive shaftthrough which said drive shaft reciprocates, a grinder-head housingsecured to the lower end of said tube enclosing the bottom of said tubeand said drive shaft, knife-grinding means mounted below said tube andseparated from said tube and said shaft by said grinder-head housing,and power transmission means between said drive shaft and said grindingmeans.

2. In a cloth cutting machine having a reciprocating knife blade and amotor for moving said blade, a sharpening device comprising aperipherally threaded hollow shaft, a circular tube positioned coaxiallyoutside said threaded shaft, a follower secured to said tube andengaging the threads on said threaded shaft, a housing removablyattached to said machine and enclosing said tube, said housing and saidtube enclosing the peripheral surface of said threaded shaft, means forrotatably supporting said threaded shaft in said housing, powertransmission means between said motor and said shaft, a noncirculardrive shaft inside said threaded shaft, a guide member fixed to saidthreaded shaft having an opening complementary to said drive shaftthrough which said drive shaft reciproeates, a grinder-head housingsecured to the lower end of said tube enclosing the bottom of said tubeand said drive shaft, rotatable circular knife-grinding means mountedbelow said tube and separated from said tube and said shaft by saidgrinder-head housing, said knife-grinding means positioned to contactthe knife blade so that their axes of rotation are inclined at an anglefrom the horizontal and having an included angle of 156 to whenprojected on a horizontal plane, and power transmission means betweensaid drive shaft and said grinding means.

3. In a cloth cutting machine having a reciprocating knife blade and amotor for moving said blade, a sharpening device comprising aperipherally threaded hollow shaft, a circular tube positioned coaxiallyoutside said threaded shaft, a follower secured to said tube andengaging the threads on said threaded shaft, a housing removablyattached to said machine and enclosing said tube, said housing and saidtube enclosing the peripheral surface of said threaded shaft, means for'rotatably supporting said threaded shaft in said housing, powertransmission means between said motor and said shaft, a noncirculardrive shaft inside said threaded shaft, a guide member fixed to saidthreaded shaft having an opening complementary to said drive shaftthrough which said drive shaft reciprocates, a grinder-head housingsecured to the lower end of said tube enclosing the bottom of said tubeand said drive shaft, rotatable circular knife-grinding means mountedbelow said tube and separated from said tube and said shaft by saidgrinder-head housing, said knifegrinding means positioned to contact theknife blade so that their axes of rotation are inclined at an angle of10 from the horizontal and having an included angle of 156 to 170 whenprojected on a horizontal plane, and power transmission means betweensaid drive shaft and said grinding means.

References Cited in the file of this patent UNITED STATES PATENTS1,815,017 Wagner July 14, 1931 1,815,018 Wagner July 14, 1931 1,884,924Van Berkel Oct..25, 1932 2,060,197 Greenbaum Nov. 10, 1936 2,282,918Zawistowski May 12, 1942 2,423,570 Steiner July 8, 1947 2,444,909Bangser July 13, 1948v 2,450,473 Goldie Oct. 5, 1948 2,480,278Zawistowski Aug. 30, 1949 2,529,441 Zawistowski Nov. 7, 1950

